The Short Answer
The verdict is depends. While period underwear is a brilliant, eco-friendly alternative to disposable products, independent lab testing revealed that 65% of tested brands contain PFAS (forever chemicals).
The good news is that you don't have to choose between ruining your clothes and exposing yourself to toxic chemicals. Brands like Saalt and Period Aisle use safe, mechanical moisture barriers. However, if you are relying on older pairs of Thinx or Knix, it is time to throw them in the trash.
Why This Matters
Your vulva and vagina are made of highly permeable mucous membranes that rapidly absorb whatever they touch. Chemicals placed in this area are absorbed directly into your bloodstream without being filtered by your liver first. Are Tampons Safe
PFAS are notorious "forever chemicals" designed to repel water, grease, and stains. Exposure to PFAS is linked to hormone disruption, fertility issues, thyroid disease, and an increased risk of cancer.
This isn't just a theoretical risk. In 2020, independent lab testing at the University of Notre Dame found 3,264 parts per million (ppm) of fluorine in a pair of Thinx organic briefs. That is a massive, intentional dose of toxic chemicals sitting against your most sensitive tissue. Does Thinx Have Pfas
The fallout from these findings was significant. Thinx settled a $5 million class-action lawsuit in 2023, and Knix followed with a $1.4 million settlement over similar PFAS contamination claims. Thinx Vs Knix
Fortunately, legislation is finally catching up to the science. California banned intentionally added PFAS in all menstrual products starting January 1, 2025. But because you can still easily buy unregulated products online, you must verify brand testing yourself.
What's Actually In Period Underwear
Understanding how period underwear works helps you spot where the toxic chemicals hide. Most pairs rely on a multi-layer system to trap blood. Period Underwear Vs Pads
- Moisture-Wicking Layer ā This is the fabric directly touching your skin. This is where PFAS are most commonly sprayed to make blood pull away from your body quickly.
- Absorbent Core ā This internal layer holds the liquid. Look for organic cotton or bamboo here, rather than cheap synthetic microfibers that harbor bacteria and odor.
- Leak-Proof Barrier ā This prevents blood from bleeding through to your pants. Safe brands use untreated PUL (polyurethane laminate) or TPU, while toxic brands rely on chemical coatings. Is Plastic In Pads Bad
- Antimicrobial Treatments ā Brands add these to prevent smell. Avoid nanosilver (Agion), which can disrupt your natural vaginal microbiome. Is Silver In Period Underwear Safe
What to Look For
Green Flags:
- Third-Party PFAS Testing ā The brand should publish independent lab results showing "non-detect" for total fluorine. Which Period Underwear Has Pfas
- OEKO-TEXĀ® Certification ā This ensures the finished fabric has been rigorously tested for a wide range of harmful substances.
- Organic Cotton ā Soft, highly breathable, and grown without synthetic pesticides that can cause irritation. Are Organic Pads Worth It
Red Flags:
- "PFOA/PFOS Free" Claims ā This is a classic greenwashing trick. There are over 12,000 types of PFAS, so claiming to be free of just two older variations means nothing.
- Proprietary Odor Control ā Trademarked antimicrobial fabrics often hide heavy metals and harsh biocides.
- Lack of Transparency ā If a brand won't explicitly state their fabrics are "PFAS-free" or "fluorine-free," assume they are contaminated.
The Best Options
You don't have to sacrifice leak protection to stay safe. These brands have verified, independent testing proving they do not use forever chemicals. Safest Period Underwear
| Brand | Product | Verdict | Why |
|---|---|---|---|
| Saalt | Wear Everyday Panties | ā | Independently tested PFAS-free with an ultra-thin, highly effective design. Is Saalt Period Underwear Clean |
| Period Aisle | Period Boxers & Briefs | ā | Uses OEKO-TEX certified organic cotton without any chemical coatings. |
| WUKA | Ultimate Period Pants | ā | Award-winning brand that strictly tests for and bans all forever chemicals. |
| Knix | Leakproof Underwear | ā ļø | Settled a $1.4M PFAS lawsuit, though they pledge increased testing moving forward. Is Knix Clean |
| Thinx | Classic Period Underwear | š« | Betrayed consumer trust with massive PFAS levels despite "organic" marketing. Is Thinx Safe |
The Bottom Line
1. Ditch your old pairs of Thinx. The extremely high levels of PFAS found in pre-2023 manufacturing are simply not worth the risk to your hormonal health.
2. Demand total fluorine testing. Don't settle for marketing fluff. Only buy from brands that publicly share their third-party lab results. Period Underwear No Pfas
3. Switch to Saalt or Period Aisle. Both brands offer exceptional leak protection using safe, mechanical barriers instead of toxic chemical sprays.
FAQ
How do PFAS get into period underwear?
Manufacturers use PFAS as a cheap shortcut to make fabrics moisture-wicking and stain-resistant. Instead of engineering higher-quality textiles, they spray synthetic fabrics with forever chemicals so blood quickly pulls away from the skin and doesn't stain the gusset. Are There Chemicals In Pads
Can washing period underwear remove PFAS?
No, washing will not make toxic underwear safe. PFAS are called "forever chemicals" because their carbon-fluorine bonds do not break down. Washing them only releases the chemicals into your local water supply, while plenty remains embedded in the fabric against your skin.
Are period underwear safer than tampons?
It depends entirely on the brand you choose. A PFAS-free pair of organic cotton period underwear is vastly safer than conventional bleached tampons. However, PFAS-coated underwear poses a much higher chemical risk than using an organic tampon. Tampons Vs Pads Safety